What is calcium?
Flip through a magazine these days, and you may get the idea that calcium is the same thing as milk (and that famous people who "get" a lot of it are always out of napkins). Those milk-mustache ads have certainly spread the word that calcium can help boost your bones. It's true that 99 percent of your body's calcium is found in your skeleton, where it works to create strong bones when you're young and prevent bone loss as you age.
Protecting your bones is not all that calcium does, however. And milk is not the only source of this important mineral. back to top
Why do I need calcium?
Calcium is best known for its role in building strong bones and teeth. But it plays an important part in other body functions as well. Calcium helps control the way your nerves send messages back and forth and the way your muscles (including your heart) contract and relax. It also helps with blood clotting and the passage of nutrients in and out of your cells.
If there's not enough calcium in your blood to do these things, your body will start stealing calcium from your bones. That's what sets in motion the early stages of osteoporosis
, a disease that causes bones to become thin and brittle and break easily. You've probably seen old women who have this disease: they're often stooped over and may even have a humpback.
But here's what many teenagers don't realize: osteoporosis isn't just a disease of old age. It starts as early as now. Getting enough calcium to build up your bones now, while your bones are still growing, is one of the best ways to prevent osteoporosis later. Another way to help keep your bones healthy—for life—is by getting plenty of certain types of exercise, such as walking, dancing, or strength training
. back to top
Can calcium help treat PMS?
Besides protecting your bones, calcium may be a special friend if you have symptoms of PMS (premenstrual syndrome)
. Studies have shown that taking a calcium supplement can help relieve unwelcome PMS symptoms such as bloating, aches and pains, food cravings, mood swings, and depression. Researchers aren't sure why calcium has this effect. It may be that some women's calcium levels drop just before they get their period and taking a calcium supplement helps correct this problem. back to top
What foods are high in calcium?
Well, there's milk, of course. (Nonfat is best.) Milk and milk products such as yogurt and cheese are convenient sources of calcium for people who don't have a problem digesting lactose
, or milk sugar. But you have plenty of other choices if you can't tolerate milk products—among them: calcium-fortified orange juice or soy milk (both of which may provide as much calcium as milk) and tofu (make sure the label says "calcium-set").
Other foods containing calcium include dark green leafy vegetables such as kale and collards, almonds, sardines with bones, broccoli, cooked dry beans and peas, and dried fruits such as apricots, figs, and raisins. (Note that spinach is not a good source of calcium because it contains ingredients called oxalates that prevent your body from absorbing the calcium.) back to top
Why would I take a calcium supplement?
If you're like most people in the United States, you don't get your recommended daily amount of calcium through your diet. Here are some examples of what you would need to eat, every day, to get enough calcium:
- four or five cups of nonfat milk or yogurt, OR
- one cup of nonfat milk, one cup of broccoli, one cup of navy beans, one cup of yogurt, and four ounces of pink salmon, OR
- five cups of cooked kale, OR
- 10 cups of cooked broccoli
If you're not sure that you're getting enough calcium through food alone, taking calcium supplements is a good insurance policy. In addition, if your goal is to try using calcium to treat symptoms of PMS
, it's probably best to take supplements because that's the form of the mineral used in studies. back to top
What is the best form to take?
The type of calcium used in studies to treat PMS
is calcium carbonate. This is the form of calcium in familiar products such as Tums and Caltrate, which you can find in any drugstore. Some people prefer calcium citrate, a form of calcium that may be easier for some people (especially older people) to absorb. You can find calcium citrate in health-food stores and some drugstores. back to top
What is a typical dose?
The recommended daily allowance (RDA) for calcium for girls ages 9 through 18 is 1,300 mg. To get this amount of calcium through milk alone, you'd have to drink more than four glasses a day.
To calculate how much calcium you should take in a supplement, think about how much you get every day in your diet. (Figure that each glass of milk, each glass of calcium-fortified orange juice, and each container of yogurt gives you about 300 mg.) Then calculate how much more calcium you would need to take in to reach your goal of 1,300 mg. It's safe to take up to 2,500 mg of calcium a day, through food and supplements combined.
Let's say your goal is to take in 1,200 mg of calcium through supplements. You can find that amount in:
- three Tums Ultra tablets (each one has 400 mg of elemental calcium)
- two Caltrate tablets (each one has 600 mg of elemental calcium)
If you're using calcium citrate, you'll need to check the label to see how much elemental calcium each tablet contains. The clerk at your health-food store may be able to help you figure out a daily dose. back to top
How do I take it?
Your body can absorb only about 500 mg of calcium at a time. So if you're taking 1,200 mg of calcium a day, you'll want to split that amount into three smaller doses.
Note that calcium carbonate is best absorbed when taken with food, especially acidic foods such as citrus fruits or orange juice. Calcium citrate, on the other hand, is best taken on an empty stomach. back to top
Are there any side effects?
Calcium supplements, especially calcium carbonate, can sometimes cause constipation or gas. If you notice these effects after starting to take a calcium supplement, try lowering your dose and building back up gradually. back to top
Steer clear of calcium supplements made from dolomite, oyster shells, or bonemeal, because they may contain unhealthy amounts of lead. Talk with your health care provider before taking calcium if you are taking any kind of prescription medication or if you have ever had kidney stones. Don't take calcium supplements at the same time as iron supplements because they may interfere with your ability to absorb the iron. Don't take calcium with tetracycline
because it may change how this drug works. Be sure to tell your doctor or health professional if you are taking any herb or supplement.
The use of herbs is not recommended during pregnancy and breast-feeding except under the guidance of a health professional. back to top